The present invention relates generally to telecommunications systems and methods and, more specifically, to a system and method for establishing and managing subconference calls within a main conference call.
Advances in telecommunications have made available teleconferencing features that more closely approximate a face-to-face meeting for individuals who are located at substantial distances from each other. For example, the higher bandwidth provided by networks such as the Integrated Services Digital Network (ISDN) enables voice, video, and textual/graphic data to be transmitted to and from each party in a teleconferencing call. The ability to include video and textual/graphic data within the teleconferencing call more closely approximates the visual presentations which are part of face-to-face meetings.
Interactions between the parties during a multimedia teleconferencing call still face substantial constraints. Subtle visual cues between parties in a face-to-face meeting can provide non-verbal information which might not be captured completely on video. Furthermore, in negotiations in which a group representing a single interest is seated together, that group will often engage in informal discussions in hushed tones while someone else at the table continues to address the entire conference. Conventional teleconferencing technology is not well suited to these types of subconferences.
Conference calls can be set up and controlled by telephone operators who selectively add and drop individuals to and from a conference call. The operators can maintain a visual display of individuals in the conference call by name and by telephone number. An improvement to the operator-controlled teleconferencing system is described in U.S. Pat. No. 4,796,293 to Blinken et al., in which a service computer performs the call set-up functions previously performed by the telephone operators. A conference call coordinator, who also participates in the call, establishes communication with the service computer from the coordinator""s computer terminal via a packetized data system. Once communication with the service computer is established, the coordinator has the same capabilities to add and drop individuals from the conference call as an operator.
U.S. Pat. No. 5,373,549 to Bales et al. describes a multi-level conference management system in which a party in a first telephone conference can combine the first telephone conference with a second telephone conference already in process. The party who coordinated the combination of the two conferences has the ability to control all of the parties on the first telephone conference, such that the coordinating party can disconnect the parties within the first telephone conference from the parties on the second conference and subsequently reconnect the parties. By disconnecting and reconnecting the first conference, the coordinating party can effectively establish a subconference call within the combined conference call.
Although the Bales et al. conference management system represents an improvement over prior teleconferencing systems, the system falls short of providing a means by which participants in a conference call can establish a subconference call without the other conference call parties being aware of the formation of the subconference call. The computer terminal of each coordinator of the combined conference call displays the names and telephone numbers of all parties in the call. Consequently, when a coordinator drops parties from the conference call to establish a subconference call, the other coordinators in the conference call are able to detect that some of the parties have been dropped. Furthermore, in order to establish a subconference call, the parties to the subconference call must first be disconnected from the conference call.
What is needed is a system and a method for transparently establishing subconference calls during a conference call in a manner which enables the subconference call parties to receive voice information from the conference call during the subconference call.
A method for managing subconference calls during a main conference call includes the steps of establishing a first subconference call and transmitting voice data over the first subconference call without transmitting the voice data over the main conference call. The first subconference call is established by providing connectivity within a subset of the terminals that are participating within the main conference call. Voice information generated at a terminal within the subset is isolated to transmissions to other terminals within the subset. However, voice information generated at a terminal participating in the main conference call, but not the first subconference call, is universally transmitted. A xe2x80x9cterminalxe2x80x9d as used herein may be a telephone or may be a computing device having telephony capabilities.
In the preferred embodiment, the invention is practiced in a packet-based data network, such as a local area network (LAN). The main conference call and the first subconference call are voice-over-data-network calls, such as internet protocol (IP) telephony calls. The main IP telephony conference call is established utilizing conventional IP telephony methods. Subsequently, a first terminal within the main conference call transmits a first subconference call request to a second terminal that is also entered in the main conference call. The first subconference call request preferably includes an option to reject the request and includes a text message indicating the intended subject matter for the first subconference call, so that a user of the second terminal can decide whether to accept the first subconference call request. A connection to the second terminal is monitored for an acceptance of the request and, if the acceptance is detected, the first subconference connection is established. The first subconference call is established in parallel with the main conference call, so that the first and second terminals remain as voice-receiving participants of the main conference call, instead of being disconnected from the main conference call. Furthermore, the call set-up procedure for the first subconference call is transparent to the other terminals on the main conference call.
During the first subconference call, voice data transmitted from the first terminal is addressed only to the second terminal and voice data transmitted from the second terminal is addressed only to the first terminal. Consequently, terminals other than the first and the second terminals in the main conference call do not receive the voice data generated in the first subconference call. Nevertheless, the voice information generated in the main conference call is mixed with voice data generated from the first and second terminals, so that the users of the first and second terminals are able to hear conversations taking place in the main conference call concurrently with the conversation taking place in the first subconference call.
Additional terminals can be added to the first subconference call, and each terminal is capable of rejoining two-way conversations within the main conference call at any time. Furthermore, each terminal in the first subconference call can transmit a request to another terminal in the main conference call to establish a second subconference call that is isolated from the main conference call and the first subconference call. For example, the second terminal might transmit a second subconference call request to a third terminal to establish a second subconference call. If the request is accepted and the second subconference is established, the second terminal can subsequently rejoin two-way conversations within either the first subconference call or the main conference call. The transfers between subconference calls and the main conference call are all transparent to the other terminals in the main conference.
A system for establishing and managing subconference calls within a main conference call includes a gatekeeper with a conference call subsystem to establish a main conference call between multiple IP telephony terminals. The gatekeeper also includes a subconference call subsystem that is responsive to a subconference call request to transmit the call request from a first terminal to a second terminal. The subconference call subsystem responds to an acceptance of the call request by establishing a first IP telephony subconference between the first and second terminals.
A data router routes voice data transmitted from terminals participating in the first subconference call exclusively to other terminals participating in the subconference call, thereby preventing the other terminals within the main conference call from receiving subconference call voice data. A multipoint control unit (MCU) mixes the voice data from the main conference call with subconference voice data for presentation of the mixed voice data at the subconference terminals. The MCU function can be centrally located, for instance in the gatekeeper, or it can be distributed in the subconference terminals.
The subconference call request can include instructions to set up a multimedia subconference call. For example, the subconference call might include a whiteboard feature for presentation of textual and graphic visual data. The MCU mixes whiteboard data from the main conference call with whiteboard data from the subconference call in a manner which distinguishes the main conference whiteboard data from the subconference whiteboard data.
The subconference call subsystem is capable of establishing a second subconference call in response to a second subconference call request from a terminal participating in the first subconference call. A subconference call transfer request triggers the subconference call subsystem to either transfer a terminal from one subconference call to another, from a subconference call to the main conference call, or from the main conference call to a subconference call.